Of all the post-war causes célèbres which have returned to haunt the justice system, the case of Ruth Ellis - the last woman to be executed in Britain - may raise the most interesting legal issues.

The conviction of Ruth Ellis is being reviewed

On Wednesday the Court of Appeal reserved judgement in the case of Ellis on whether she should have been hanged for the murder of her lover - racing driver David Blakely - in Hampstead, north London in 1955.

Ellis's family have argued that the verdict be reduced to manslaughter saying that she suffered from "battered woman syndrome".

The question of what constitutes provocation is one of the legal issues that the case has thrown up and whether the jury should have been allowed by the judge to consider that as a defence.

And, if a defendant withholds information from the court, which may have aided his or her case, does that undermine the safety of the conviction?

Finally, what account should be taken now of a home secretary who may have placed support for the death penalty above serious consideration of the argument for a reprieve.

State of mind

In 2000, the Law Lords significantly widened the defence of provocation by recognising women subject to severe abuse may argue that their loss of self-control was caused, not just by anger, but by fear and despair.

Ellis did not help her case by responding to the single question asked of her by prosecuting counsel: "It is obvious that when I shot him [David Blakely], I intended to kill him

But one thing the Court of Appeal would not do in the Ellis case was to superimpose this template - the "battered woman" defence - on a trial which took place 48 years ago.

This would be retrospective justice and alien to English law.

The key issue is whether the trial judge erred, as the law stood at the time, by depriving her of a legitimate line of defence when he ruled the 28-year-old mother, a nightclub hostess, could not plead provocation.

Certainly, Ellis did not help her case by responding to the single question asked of her by prosecuting counsel: "It is obvious that when I shot him [David Blakely], I intended to kill him."

But would the jury at the original Old Bailey trial have taken a more sympathetic view if they had been able to place more weight on her state of mind at the time of the shooting?

In 1955 there was no defence of diminished responsibility.

The defence of provocation which could lead to a manslaughter verdict could only be used in the case of a sudden loss of self-control in immediate response to a provocative act.

The Ellis case is one of a number, in which the appellant is long dead, to reach the Appeal Court.

There is little urgency in such cases - except for living relatives - and, since it was referred by the Criminal Cases Review Commission in February 2002, other appeals, where the subject is still in prison, have reached the court ahead of it.

A spokeswoman for the CCRC said there are many factors which determine which cases get priority, including the age or health of witnesses, the possible deterioration of scientific evidence and the legal issue raised.